Throughout this specification the use of the word “inventor” in singular form may be taken as reference to one (singular) Inventor or more than one (plural) inventor of the present invention. The discussion throughout this specification comes about due to the realisation of the inventor(s) and/or the identification of certain prior art problems by the inventors.
The inventors have realised that in, for example, a radio frequency identification (“RFID”) transponder, and more particularly to an RFID transponder that is used in orientation independent and/or random orientation applications, the power supplied to components of the transponder can not be assured. For example, the power supplied to a memory resident in the transponder and which is adapted to store data can not be considered reliable in random and/or independent orientation environments. In these environments, in the event that the transponder orientation is changed and/or switched, power to the transponder and/or its components is lost, and as a result, data resident in the memory may be lost.
The inventors have also realised that some manner of storage of data, which is adapted to maintain the data, for example for a period of time greater than the power outage, is considered desirable. Furthermore, the inventors have realised that such a data store should also be adapted to validly maintain data stored in the memory for a period of time which provides a relatively long retention time. The period of time may be longer than the power outage, adapted to overcome switching of field during orientation changes and/or for any period of time as may be determined by the applications and/or environment to which the transponder or other device is applied.
U.S. Pat. No. 7,259,654 (also by the present applicant(s)) discloses a radio frequency identification transponder including a power supply and a memory array which stores data. When power from the power supply ceases to be provided, the data in the memory array is validly maintained for a predetermined period of time. The period of time is determined by discharging of the memory array through stray leakage paths within the memory array.
The inventors have realised that improvements can be made in the time data is validly maintained in a transponder. This comes about, in part, by the inventors identifying that leakage may be at least partially controlled and/or reduced.
The inventors have also realised that leakage, such as the stray leakage as disclosed in U.S. Pat. No. 7,259,654, is not the only leakage which may determine the time data is validly maintained in a transponder.
Any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material forms a part of the prior art base or the common general knowledge in the relevant art in Australia or elsewhere on or before the priority date of the disclosure and claims herein.